Trays with multiple wells can be used for simultaneously exposing multiple tissue samples to liquids. A sample may be held in a perforated container which is then mated with a well in order to expose the tissue to the liquid. In order to facilitate exposure of multiple (6, 12, 24, 96, etc.) samples simultaneously, multiple containers may be attached to one another. Enough liquid must be present in each well to treat each sample. When such containers are rigidly attached, variations on in the depth of the well or the depth of the containers may prevent the very bottom of the container from seating in the very bottom of the well. If the sample happens to come to rest at the very bottom of the well, then only a minimum of liquid is needed to fully immerse the sample. But if the sample comes to rest anywhere above the bottom of the well, additional liquid will be required to fully immerse the sample.